Do consider that per FAR 107 (I believe... don't have the rules in front of me right now.) flying beyond LOS is illegal. Just don't get caught by the FAA! Try and put the most efficient power system in that you can find, and keep it light. If you can belly land, save yourself some weight and drag and go without gear. It'll also make you more flexible in the event that you need to make an en-route emergency landing. Try to keep a suitable landing site within glide.